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Clear lens extraction after laser peripheral iridotomy significantly reduces IOP
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Clear lens extraction not only reduced IOP, but also caused angle widening and reduced the requirement for ocular hypotensive medications in eyes with primary angle closure and persistently raised IOP after laser peripheral iridotomy, according to Tanuj Dada, MD, and colleagues in the Journal of Cataract & Refractive Surgery.
Researchers included 44 phakic eyes of 44 patients older than 50 years with primary angle closure, corrected distance visual acuity of 20/20 or better with a patent laser peripheral iridotomy (LPI) and an IOP of more than 25 mm Hg at least 8 weeks after LPI. All eyes had clear lens extraction by phacoemulsification, and researchers defined success as an IOP less than 18 mm Hg without medications at 12 months.
The mean preoperative IOP of 27.1 mm Hg decreased to 13.2 mm Hg at 12 months. The angle opening distance at 500 µm increased from baseline values at 0 degrees, from 0.104 mm to 0.31 mm, and 180 degrees, from 0.202 mm to 0.412 mm.
The trabecular iris angle also increased at 0 degrees and 180 degrees, according to the study.
Researchers found absolute success in 38 eyes (86.3%).
They noted a significant negative correlation between the lens thickness and the anterior chamber depth and between the lens thickness and the angle opening distance 500 µm from scleral spur at the 0-degree angle.
“There could be merit in proceeding with lens extraction without performing an LPI in eyes with primary angle closure,” the researchers wrote. – by Abigail Sutton
Disclosure: The researchers reported no relevant financial disclosures.
Perspective
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Carl H. Jacobsen, OD, FAAO
Primary angle closure glaucoma is a relatively rare problem in the U.S., accounting for less than 10% of glaucoma cases, but an acute angle closure attack may lead to blindness within days.
Correctly identifying those at risk of primary angle closure (PAC) is of paramount importance in preventing primary angle closure glaucoma (PACG).
During my training I was led to believe that a laser peripheral iridotomy (LPI) essentially eliminates PAC risk, but this is not the case. LPI eliminates pupil block, the most common cause of PAC, but there are other factors at play.
Dada and colleagues, through their prospective case series, provide some insight into an important factor contributing to PAC, the mature crystalline lens. They found that in patients with PAC who had persistent IOP elevation after LPI, lens removal was successful in significantly reducing IOP.
Pupil block is responsible for acute angle closure, but crowding of the anterior chamber by the crystalline lens may restrict aqueous outflow and elevate IOP in a less dramatic fashion. Of course, patients who have visually significant cataracts and PAC are well advised to undergo cataract surgery.
There is mounting evidence, this study included, in support of clear lensectomy as a treatment for persistent PAC following LPI.
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